Axle assembly having wheel hubs configured for use in vehicle with central tire inflation system

ABSTRACT

An axle assembly, including an axle shaft, annular member, hub, inner and outer hub bearings, abutment ring, first and second seals, and an air inlet port. The annular member is disposed about the axle shaft. The hub is coupled for rotation with the axle shaft and defines an outlet port. The first and second shaft seals form seals between the hub and the annular member. The air inlet port is mounted to one of the annular member and the abutment ring and includes an inlet boss. A first fluid conduit is defined by the abutment ring or both the abutment ring and the inlet port. The first fluid conduit is in fluid communication with the air inlet boss. The second shaft seal is spaced apart from the first shaft seal along the rotational axis to at least partially define a second fluid conduit in fluid communication inlet and outlet ports.

FIELD

The present disclosure relates to an axle assembly having wheel hubsconfigured for use in a vehicle with a central tire inflation system.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Onboard central tire inflation systems (“CTI systems”) are used on manytypes of vehicles to provide pressurized air to inflate, or maintaintire pressure from a centralized unit. However, current CTI systems arebulky or complex, leading to increased cost, size, and weight of the CTIsystems and vehicles employing them. As such, there is a need for morecompact CTI systems.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for an axle assembly including an annularmember, a hub, inner and outer hub bearings, a first shaft seal, asecond shaft seal, and an air inlet port. The annular member is disposedabout a rotational axis and includes an inboard end. The hub is coupledto the annular member for rotation about the rotational axis and isconfigured to be coupled to a wheel. The hub defines an outlet port. Theinner and outer hub bearings support the hub for rotation on the annularmember. The abutment ring is fixedly mounted to the annular member. Thefirst shaft seal forms a seal between the hub and the annular member.The second shaft seal forms a seal between the hub and the annularmember. The air inlet port is mounted to one of the annular member andthe abutment ring. The air inlet port has an inlet boss. A first fluidconduit is defined by the abutment ring or both the abutment ring andthe inlet port. The first fluid conduit is in fluid communication withthe air inlet boss. The second shaft seal is spaced apart from the firstshaft seal along the rotational axis to at least partially define asecond fluid conduit. The second fluid conduit couples the outlet portin fluid communication with the first fluid conduit.

The present teachings further provide for an axle assembly includinginboard and outboard ends, a steering knuckle, a hub, inner and outerhub bearings, first and second seals, and an abutment ring. The steeringknuckle includes an annular member, and an air inlet port. The annularmember is disposed about a rotational axis. The annular member includesan outer radial surface, an inner radial surface, and a channel definedby the outer radial surface. The air inlet port is disposed within thesteering knuckle at the inboard end. The air inlet port includes aninlet boss extending radially inward from an outer surface of thesteering knuckle and terminating radially outward of the inner radialsurface of the annular member. The hub is rotatably coupled to theannular member for rotation about the rotational axis, and includes anouter radial surface, an inner radial surface, and an outlet port. Theoutlet port includes an outlet boss extending from an outboard surfaceof the hub toward the inboard end. The inner and outer hub bearings aredisposed between the steering knuckle and the inner radial surface ofthe hub, and are configured to allow rotation of the hub about thesteering knuckle. The outer hub bearing is disposed outboard of theinner hub bearing and radially inward of the outlet port. The first sealis disposed outboard of the inner hub bearing and radially between thehub and the steering knuckle, and configured to form a sealtherebetween. The second seal is disposed outboard of the first seal,inboard of the outer hub bearing, and radially between the hub and thesteering knuckle, and configured to form a seal therebetween. Theabutment ring is disposed inboard of the inner hub bearing. The abutmentring has an inboard portion and an outboard portion. The outboardportion is radially between the hub and the outer radial surface of theannular member. The inboard portion extends radially outward from theoutboard board portion. The abutment ring defines a first pocket influid communication with the inlet boss. The first pocket extends fromthe inlet boss and toward the outboard end. The channel extends from thefirst pocket toward the outboard end and terminates inboard of the outerhub bearing. The channel is radially inward of the inner hub bearing andthe first seal. The annular member, the hub, and the first and secondseals define a second pocket that extends radially outward from thechannel, axially between the first and second seals, and terminatesradially inward of the outer radial surface of the hub. The secondpocket is in fluid communication with the outlet port.

The present teachings further provide for an axle assembly includinginboard and outboard ends, an axle shaft, an axle housing, a hub, innerand outer hub bearings, first and second seals, and an abutment ring.The axle shaft is rotatably disposed about a rotational axis and adaptedon the outboard end to drive a wheel. The axle housing includes anannular member disposed about the axle shaft. The annular memberincludes an outer radial surface, an inner radial surface, and a channeldefined by the outer radial surface. The hub is coupled to the axleshaft and includes an outer radial surface, an inner radial surface, andan outlet port. The outlet port includes an outlet boss extending froman outboard surface of the hub toward the inboard end. The inner andouter hub bearings are disposed between the axle housing and the innerradial surface of the hub, and are configured to allow rotation of thehub about the axle housing. The outer hub bearing is disposed outboardof the inner hub bearing and radially inward of the outlet port. Thefirst seal is disposed outboard of the inner hub bearing and radiallybetween the hub and the axle housing, and configured to form a sealtherebetween. The second seal is disposed outboard of the first seal,inboard of the outer hub bearing, and radially between the hub and theaxle housing, and configured to form a seal therebetween. The abutmentring is disposed inboard of the inner hub bearing. The abutment ring hasan inboard portion and an outboard portion. The outboard portion isradially between the hub and the outer radial surface of the annularmember. The inboard portion extends radially outward from the outboardboard portion. The abutment ring defines an air inlet port including aninlet boss extending radially inward from an outer radial surface of theabutment ring. A first fluid conduit is defined by the abutment ring orboth the abutment ring and the outer radial surface of the annularmember. The first fluid conduit extends from the inlet boss and towardthe outboard end of the annular member. The channel extends from thefirst pocket toward the outboard end and terminates inboard of an outerhub bearing. The channel is radially inward of the inner hub bearing andthe first seal. The annular member, the hub, and the first and secondseals define a second pocket that extends radially outward from thechannel, axially between the first and second seals, and terminatesradially inward of the outer radial surface of the hub. The secondpocket is in fluid communication with the outlet port.

The present teachings further provide for an axle system for use withcentral tire inflation systems including an annular member, a hub, anabutment ring, an air inlet port, a first pocket, at least one channel,a first and second seal, a second pocket, and an outlet port. Theannular member is disposed about a rotational axis of an axle. Theannular member includes an inboard end, an outboard end, an outer radialsurface, and an inner radial surface. The outboard end is proximal to awheel. The inboard end is axially opposite the outboard end and distalto the wheel. The hub is disposed about the rotational axis of the axleand rotatably coupled to the annular member to allow rotation of the hubabout the rotational axis of the axle. The hub includes an inboard end,an outboard end, an outer radial surface, and an inner radial surface.The outboard end of the hub is proximal to the wheel. The inboard end ofthe hub axially opposite the outboard end of the hub and distal to thewheel. The inner radial surface of the hub is supported about theannular member by an inner hub bearing. The abutment ring is disposedinboard of the inner hub bearing. The abutment ring has an inboardportion and an outboard portion. The outboard portion extends axiallytoward the outboard end of the annular member and is radially betweenthe hub and the outer radial surface of the annular member. The inboardportion extends axially toward the inboard end of the annular member andradially outward from the outboard board portion. The air inlet port isdisposed at the inboard end of the annular member, and includes an inletboss extending radially inward from an outer radial surface of one ofthe annular member and the abutment ring. The first pocket is defined bythe abutment ring and the annular member. The first pocket is in fluidcommunication with the inlet boss. The first pocket extends from theinlet boss and toward the outboard end of the annular member. The atleast one channel is defined by the outer radial surface of the annularmember. The at least one channel extends from the first pocket towardthe outboard end of the annular member, and terminates inboard of anouter hub bearing. The at least one channel is radially inward of theinner hub bearing. The first seal is disposed outboard of the inner hubbearing, radially outward of the at least one channel, and radiallybetween the hub and the annular member. The first seal is configured toform a hermetic seal between the hub and the annular member, whileallowing rotation of the hub about the annular member. The second sealis disposed outboard of the first seal, inboard of the outer hubbearing, and radially between the hub and the annular member. The secondseal is configured to form a hermetic seal between the hub and theannular member, while allowing rotation of the hub about the annularmember. The second pocket is defined by the annular member, the hub, andthe first and second seals. The second pocket extends radially outwardfrom the at least one channel and is in fluid communication with the atleast one channel. The second pocket extends between the first andsecond seals, and terminates radially inward of the outer radial surfaceof the hub. The outlet port is in fluid communication with the secondpocket. The outlet port includes an outlet boss extending from anoutboard surface of the hub toward the inboard end of the hub. Theoutlet port is radially outward of the outer bearing. The axle systemmay further include a channel ring disposed radially inward of the firstand second seals, radially outward of the outer radial surface of theannular member, and axially between the inner and outer bearings. Thechannel ring abuts an outboard side of the inner hub bearing and forms aseal therebetween. The inlet boss may extend radially inward from anouter radial surface of the annular member to join with the firstpocket. The inlet boss may extend radially inward from an outer radialsurface of the abutment ring to join with the first pocket. The outboardportion of the abutment ring may abut an inboard side of the inner hubbearing and form a seal therebetween. The at least one channel may bepositioned on a compressive stress quadrant of the annular member and anunloaded section of the inner hub bearing. The at least one channel mayinclude a plurality of channels. The annular member may be coupled to asteering knuckle. The annular member may be an axle housing configuredto house an axle shaft.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a representative vehicle including a central tire inflationsystem with front and rear axle assemblies in accordance with thepresent teachings;

FIG. 2 is a cross-section view of the front axle assembly of FIG. 1;

FIG. 3 is a cross-section view of the rear axle assembly of FIG. 1;

FIG. 4 is a detailed view of a portion of the front and rear axleassemblies of FIG. 2 and FIG. 3;

FIG. 5 is a detailed view of a portion of the front axle assembly ofFIG. 2; and

FIG. 6 is a detailed view of a portion of the rear axle assembly of FIG.5.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

The present teachings are directed to an axle assembly for use with acentral tire inflation system. The axle assembly can be incorporated ina vehicle, such as an automobile, sport utility vehicle, truck, tractor,machine, or any other vehicle having inflatable tires. The axle assemblyconveys pressurized air from the central tire inflation system to thetires of the vehicle to inflate the tires or maintain a predeterminedpressure within the tires. While the present teachings refer to “air” asthe inflation gas, it is understood that the system can be used withother gasses or mixtures of gasses to maintain tire inflation, such asnitrogen for example. Accordingly, the term “air” used herein is definedas encompassing those other inflation gasses or mixtures.

FIG. 1 illustrates a side view of an exemplary vehicle 10 having acentral tire inflation system (“CTIS”) 14, a front axle assembly 18, anda rear axle assembly 22. While the vehicle 10 is illustrated as a truck,it is understood that any appropriate type of vehicle may be used inaccordance with the present teachings. It is also understood that whilethe CTIS 14 of the exemplary vehicle is coupled to the front axleassembly 18 and the rear axle assembly 22 to distribute pressurized airthereto, as will be explained further, the CTIS 14 may alternatively becoupled to only the front or only the rear axle assemblies 18, 22.Furthermore, the exemplary vehicle 10 shown has six axle assembliesconfigured to be coupled to six wheels having tires 26: left front wheel30, two left rear wheels 34, and complementary right side wheels (notshown). However, it is understood that a vehicle may have any number offront and/or rear axle assemblies configured to be coupled to any numberof wheels, such as a vehicle with only two rear wheels, or with morerear wheels for example. Additionally, it is understood that the rearaxle assemblies can be located on a detachable trailer, such as on atractor trailer vehicle for example.

The CTIS 14 can include an air supply 38 and at least one conduit 42.The air supply 38 can be any type of device configured to providepressurized air to the conduit 42, such as a pump or a container ofpressurized air for example. In the case of the air supply 38 being apump, the pump can be driven by any number of means, such as anelectrical motor, the vehicle engine, or an auxiliary engine forexample. The conduit 42 can be coupled for fluid communication with theair supply 38. The conduit 42 can include any number of branches 46running to any number of front and rear axle assemblies 18, 22 to conveythe pressurized air thereto.

With regard to FIGS. 2 and 3, the axle assemblies 18, 22 are illustratedas cross-section views split at a rotational axis 50. The axleassemblies 18, 22 have an inboard end 54 proximal to the center of thevehicle 10, and an outboard end 58 opposite the inboard end 54 andconfigured to have a wheel with a tire mounted thereto. The axleassemblies 18, 22 can include an annular member 62, a hub 66, an innerhub bearing 70, an outer hub bearing 74, an abutment ring 78, a firstseal 82, a second seal 86, and an air inlet port 90. The axle assemblies18, 22 can also include a channel ring 94, and a third seal 96. The hub66 can be rotatably disposed about the rotational axis 50.

The annular member 62 can be disposed about the rotational axis 50 andextend from the inboard end 54 toward the outboard end 58. Wheninstalled on the vehicle 10, the annular member 62 is rotationally fixedrelative to the rotational axis 50. The annular member 62 can include anouter radial surface 98, an inner radial surface 102, and a channel 106at least partially defined by the outer radial surface 98. The radialdistance from the axis 50 to the outer radial surface 98 and to theinner radial surface 102 can vary along the length of the annular member62. The channel 106 can be a groove formed in at least part of the outerradial surface 98 and running axially, i.e. longitudinally, along theannular member 62, and will be described in greater detail below.

The air inlet port 90 can be located proximal to the inboard side of theaxle assembly 18, 22 for receiving pressurized air from the conduit 42.The air inlet port 90 can be disposed in either the abutment ring 78(best shown in FIG. 6) or the annular member 62 (best shown in FIG. 5).The air inlet port 90 can include an inlet boss 110 extending radiallyinward from either an outer surface 114 of the annular member 62 or anouter surface 118 of the abutment ring 78. The air inlet port 90 can beperpendicular to the rotational axis 50, but it is understood that theair inlet port 90 can also be formed at an angle relative to therotational axis 50. The inlet boss 110 can terminate radially outward ofthe inner radial surface 102 of the annular member 62 such that theinlet boss 110 does not fully penetrate through the annular member 62. Afirst portion 122 of the inlet boss 110 can be threaded to accept athreaded fitting (not shown) for fluidly coupling the conduit 42 to theair inlet port 90.

The hub 66 can include an outer radial surface 126, an inner radialsurface 130, and an outlet port 134. The outlet port 134 can include anoutlet boss 138 penetrating an outboard surface 142 of the hub 66 andextending therefrom toward the inboard end 54. The outlet boss 138 canbe substantially parallel to the rotational axis 50. A second portion146 of the outlet boss 138 can be threaded to accept a threaded fitting(not shown) for fluidly coupling the outlet boss 138 to the wheel 30, or34, and tire 26. The hub 66 can generally include at least one ofmounting feature 150, such as a bore or lug for example, for fixedlymounting the wheel to the hub 66. A brake rotor 154 can also be mountedto the hub 66 to rotate therewith.

The inner hub bearing 70 and outer hub bearing 74 can be radiallybetween the annular member 62 and the inner radial surface 130 of thehub 66. The outer hub bearing 74 is spaced axially apart from the innerhub bearing 70 and is outboard of the inner hub bearing 70, whileradially inward of the outlet port 134 and the outlet boss 138. Theinner and outer hub bearings 70, 74 can be of any suitable type ofbearing, such as roller or thrust bearings for example, and can also betapered or angled. Accordingly, the inner and outer hub bearings 70, 74each include an inner race 158, 162 and an outer race 166, 170respectively. The inner races 158, 162 can abut the outer radial surface98 of the annular member 62. The outer races 166, 170 can abut the innerradial surface 130 of the hub 66. In this way, the inner and outer hubbearings 70, 74 can support the hub 66 on the annular member 62 andallow rotation of the hub 66 about the annular member 62. The inner andouter hub bearings 70, 74 can be lubricated by grease or oil.

The first seal 82 can be disposed outboard of the inner hub bearing 70and radially between the hub 66 and the annular member 62. The firstseal 82 can be configured to form a seal between the hub 66 and thechannel ring 94. The second seal 86 can be axially apart from andoutboard of the first seal 82, while inboard of the outer hub bearing74. The second seal 86 can be radially between the hub 66 and theannular member 62. The second seal 86 can be configured to form a sealbetween the hub 66 and the channel ring 94. The first and second seals82, 86 can be designed to withstand air pressure on one side, and oil orgrease on the other, such that the seals 82, 86 can act to keep thepressurized air and any bearing lubricants separate.

With specific regard to FIGS. 5 and 6, the abutment ring 78 can beinboard of the inner hub bearing 70 and can have an inboard portion 174proximal to the inboard end 54, and an outboard portion 178 proximal tothe outboard end 66. The abutment ring 78 can be rotationally fixedrelative to the annular member 62. The outboard portion 178 can beradially between the hub 66 and the outer radial surface 98 of theannular member 62. The outboard portion 178 can abut and form a sealwith an inboard side 182 of the inner hub bearing 70 to encapsulate aportion of the channel 106. The outboard portion 178 can include a firstannular groove 186 for receiving a first o-ring 190. The first o-ring190 can form the seal between the inner race 158 of the inner hubbearing 70 and the abutment ring 78. The inboard portion 174 can extendradially outward from the outboard portion 178, such that the inboardportion 174 has a larger outer radius than the outboard portion 178. Theinboard portion 174 can abut and form a seal with the annular member 62.The inboard portion 174 can include a second annular groove 194 forreceiving a second o-ring 198. The second o-ring 198 can form the sealbetween the abutment ring 78 and the annular member 62. As shown in FIG.5, the second annular groove 194 can be formed in an outermost radialsurface 200 of the inboard portion 174 to allow the second o-ring 198 toform a seal with a shoulder 204 on the annular member 62. As shown inFIG. 6, the second annular groove 194 can alternatively be formed in aninner radial surface 208 of the inboard portion 174 to allow the secondo-ring 198 to form a seal with the outer radial surface 98 of theannular member 62. The abutment ring 78 and the annular member 62 candefine a first pocket 202 therebetween. The first pocket 202 can be influid communication with the inlet boss 110 and can extend from theinlet boss 110 toward the outboard end 58, between the outboard portion178 and the annular member 62. The first pocket 202 can be in fluidcommunication with the channel 106 to allow air to flow from the inletport 90 to the channel 106.

The third seal 96 can be located radially between the outboard portion178 of the abutment ring 78 and the hub 66, and form a sealtherebetween. The third seal 96 can prevent contaminants frompenetrating between the hub 66 and the abutment ring 78 and reaching theinner hub bearing 70, while preventing leakage of bearing lubrication.

Returning to FIGS. 2 and 3 generally, the channel 106 can be formed inthe outer radial surface 98 of the annular member 62 as an open channeland can extend from the first pocket 202 toward the outboard end 58. Thechannel 106 can terminate inboard of the outer hub bearing 74, with thechannel 106 being radially inward of the inner hub bearing 70 and thefirst seal 82. Since the channel 106 is openly formed in the outerradial surface 98, the abutment ring 78 and an inner radial surface 210(best shown in FIG. 4) of the inner race 158 can encapsulate a portionof the channel 106. The channel ring 94 can also encapsulate a portionof the channel 106 as will be discussed in detail below. The channel 106can be located at a compressive stress quadrant of the annular member 62and an unloaded section of the inner hub bearing 70. Generally, suchcompressive stress quadrant and unloaded section are located at the topof the annular member 62 relative to the ground when the axle assemblies18, 22 are installed on the vehicle 10. This location of the channel 106minimizes the stress concentration on the channel 106 and on the innerhub bearing 70 due to the channel 106 geometry and the weight of thevehicle 10. The channel 106 eliminates the need for a separate bearingcarrier and a larger diameter inner hub bearing. Thus, the axleassemblies 18, 22 can be accommodated on axle designs with limitedradial space, such as imposed by a specific diameter of brake disc forexample. Multiple channels 106 may also be used to reduce stressconcentrations on any individual channel 106.

A second pocket 214 can be defined by the channel ring 94, the hub 66,and the first and second seals 82, 86. The second pocket 214 extendsradially outward from the channel ring 94, and is axially between thefirst and second seals 82, 86. The second pocket 214 can terminateradially inward of the outer radial surface 126 of the hub 66 and canextend to the outlet boss 138 to be in fluid communication with theoutlet port 134.

With specific regard to FIG. 4, the channel ring 94 can be radiallyinward of the first and second seals 82, 86 and radially outward of theouter radial surface 98 of the annular member 62. The channel ring 94can extend over at least a portion of the channel 106. The first andsecond seals 82, 86 can form a seals between the channel ring 94 and theinner radial surface 130 of the hub 66. The channel ring 94 can form aseal with the outer radial surface 98 of the annular member 62 toencapsulate a portion of the channel 106. The channel ring 94 can beaxially between the inner and outer hub bearings 70, 74, such that aninboard side 218 of the channel ring 94 can abut and form a seal with anoutboard side 222 of the inner race 158 of the inner hub bearing 70. Theinboard side 218 can include a third annular groove 226 and a thirdo-ring 230 accepted therein for forming the seal. An outboard side 234of the channel ring 94 can abut an inboard side 238 of the inner race234 of the outer hub bearing 74. The outboard side 234 can include afourth annular groove 242 for accepting a fourth o-ring 246 therein toform a seal with the inboard side 238, the annular member 62, or both.The channel ring 94 can be rotationally fixed relative to the annularmember 62. The channel ring 94 can include an aperture 250 penetratingradially outward through the channel ring 94, to fluidly couple thechannel 106 with the second pocket 214.

Thus by the present teachings, the inlet port 90, inlet boss 110, firstpocket 202, channel 106, second pocket 214, outlet boss 138, and outletport 134 are fluidly coupled to form a flow path for pressurized airthat flows directly between the inner race 158 of the inner hub bearing70 and the annular member 62 then radially outward between the inner andouter hub bearings 70, 74.

With specific regard to the front axle assembly 18, as illustrated inFIG. 2, the annular member 62 can be coupled to a steering knuckle 254.Generally, for the front axle assembly 18, the inlet port 90 can beformed in the annular member 62 or a portion of the steering knuckle 254(best shown in FIG. 5). However, it will be appreciated that the inletport 90 can be formed in the abutment ring 78 as shown in FIG. 6. In thecase where the front wheels of the vehicle 10 are driven by the engine,such as in a front-wheel drive, or all-wheel drive vehicle for example,the front axle assembly 18 can include an axle shaft (not shown)rotatably disposed about the rotational axis 50 and radially inward ofthe annular member 62. The axle shaft can be adapted to receiverotational input on the inboard end 54 and be coupled to the hub 66 todrive the wheel on the outboard end 58.

With specific regard to the rear axle assembly 22, as illustrated inFIG. 3, the annular member 62 can be an axle housing. Generally, for therear axle assembly 22, the inlet port 90 is formed in the abutment ring78 (best shown in FIG. 6). However, it will be appreciated that theinlet port 90 can be formed directly in a portion of the annular member62 as shown in FIG. 5. The rear axle assembly 22 can include an axleshaft 258 rotatably disposed about the rotational axis 50, radiallyinward of the annular member 62, and coupled to the hub 66 on theoutboard end 58. In the case where the rear wheels of the vehicle 10 aredriven by the engine, the axle shaft 258 can be adapted to receiverotational input on the inboard end 54 and drive the wheel on theoutboard end 58.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

What is claimed is:
 1. An axle assembly comprising: an annular memberdisposed about a rotational axis, the annular member including aninboard end; a hub coupled to the annular member for rotation about therotational axis and configured to be coupled to a wheel, the hubdefining an outlet port; inner and outer hub bearings supporting the hubfor rotation on the annular member; an abutment ring fixedly mounted tothe annular member; a first shaft seal that forms a seal between the huband the annular member; a second shaft seal that forms a seal betweenthe hub and the annular member; and an air inlet port mounted to one ofthe annular member and the abutment ring, the air inlet port having aninlet boss; wherein a first fluid conduit is defined by the abutmentring or both the abutment ring and the inlet port, the first fluidconduit being in fluid communication with the air inlet boss; andwherein the second shaft seal is spaced apart from the first shaft sealalong the rotational axis to at least partially define a second fluidconduit, the second fluid conduit coupling the outlet port in fluidcommunication with the first fluid conduit.
 2. The axle assembly ofclaim 1, wherein a seal member is disposed between the inner hub bearingand the abutment ring.
 3. The axle assembly of claim 1, wherein thefirst fluid conduit is formed in part by grooves formed on the annularmember.
 4. The axle assembly of claim 3, wherein the grooves arepositioned on a compressive stress quadrant of the annular member. 5.The axle assembly of claim 1, wherein the air inlet port is integrallyand unitarily formed with the annular member.
 6. The axle assembly ofclaim 1, further comprising an axle shaft rotatably disposed about therotational axis, the axle shaft being substantially within the annularmember, and the axle shaft being coupled to the hub and adapted to drivea wheel thereon.
 7. An axle assembly comprising: an inboard end and anoutboard end; a steering knuckle including: an annular member disposedabout a rotational axis, the annular member including an outer radialsurface, an inner radial surface, and a channel defined by the outerradial surface; and an air inlet port disposed within the steeringknuckle at the inboard end, the air inlet port including an inlet bossextending radially inward from an outer surface of the steering knuckleand terminating radially outward of the inner radial surface of theannular member; a hub coupled for rotation about the rotational axis androtatably coupled to the annular member, the hub including an outerradial surface, an inner radial surface, and an outlet port, the outletport includes an outlet boss extending from an outboard surface of thehub toward the inboard end; inner and outer hub bearings disposedbetween the steering knuckle and the inner radial surface of the hub,and configured to allow rotation of the hub about the steering knuckle,the outer hub bearing disposed outboard of the inner hub bearing andradially inward of the outlet port; a first seal disposed outboard ofthe inner hub bearing and radially between the hub and the steeringknuckle, and configured to form a seal therebetween; a second sealdisposed outboard of the first seal, inboard of the outer hub bearing,and radially between the hub and the steering knuckle, and configured toform a seal therebetween; and an abutment ring disposed inboard of theinner hub bearing, with an inboard portion and an outboard portion, theoutboard portion is radially between the hub and the outer radialsurface of the annular member, the inboard portion extending radiallyoutward from the outboard board portion, the abutment ring defining afirst pocket in fluid communication with the inlet boss, the firstpocket extending from the inlet boss and toward the outboard end;wherein the channel extends from the first pocket toward the outboardend and terminates inboard of the outer hub bearing, the channel isradially inward of the inner hub bearing and the first seal; and whereinthe annular member, the hub, and the first and second seals define asecond pocket extending radially outward from the channel, axiallybetween the first and second seals, and terminating radially inward ofthe outer radial surface of the hub, the second pocket is in fluidcommunication with the outlet port.
 8. The axle assembly of claim 7,further comprising a channel ring disposed radially inward of the firstand second seals, radially outward of the outer radial surface of theannular member, and axially between the inner and outer hub bearings,the channel ring abuts an outboard side of the inner hub bearing andforms a seal therebetween.
 9. The axle assembly of claim 7, wherein thechannel is positioned on a compressive stress quadrant of the annularmember and an unloaded section of the inner hub bearing.
 10. The axleassembly of claim 7, wherein the channel includes a plurality ofchannels.
 11. The axle assembly of claim 7, wherein the outboard portionof the abutment ring abuts an inboard side of the inner hub bearing andforms a seal therebetween.
 12. The axle assembly of claim 7, furthercomprising an axle shaft rotatably disposed about the rotational axis,the axle shaft being substantially within the annular member, and theaxle shaft being coupled to the hub on the outboard end and adapted todrive a wheel thereon.
 13. An axle assembly comprising: an inboard endand an outboard end; an axle shaft rotatably disposed about a rotationalaxis, the axle shaft being adapted on the outboard end to drive a wheel;an axle housing including an annular member disposed about the axleshaft, the annular member including an outer radial surface, an innerradial surface, and a channel defined by the outer radial surface; a hubcoupled to the axle shaft and including an outer radial surface, aninner radial surface, and an outlet port, the outlet port includes anoutlet boss extending from an outboard surface of the hub toward theinboard end; inner and outer hub bearings disposed between the axlehousing and the inner radial surface of the hub, and configured to allowrotation of the hub about the axle housing, the outer hub bearingdisposed outboard of the inner hub bearing and radially inward of theoutlet port; a first seal disposed outboard of the inner hub bearing andradially between the hub and the axle housing, and configured to form aseal therebetween; a second seal disposed outboard of the first seal,inboard of the outer hub bearing, and radially between the hub and theaxle housing, and configured to form a seal therebetween; and anabutment ring disposed inboard of the inner hub bearing, with an inboardportion and an outboard portion, the outboard portion is radiallybetween the hub and the outer radial surface of the annular member, theinboard portion extending radially outward from the outboard boardportion, the abutment ring defining an air inlet port including an inletboss extending radially inward from an outer radial surface of theabutment ring; wherein a first fluid conduit is defined by the abutmentring or both the abutment ring and the outer radial surface of theannular member, the first fluid conduit extending from the inlet bossand toward the outboard end of the annular member; wherein the channelextends from the first pocket toward the outboard end and terminatesinboard of an outer hub bearing, the channel is radially inward of theinner hub bearing and the first seal; and wherein the annular member,the hub, and the first and second seals define a second pocket extendingradially outward from the channel, axially between the first and secondseals, and terminating radially inward of the outer radial surface ofthe hub, the second pocket is in fluid communication with the outletport.
 14. The axle assembly of claim 13, further comprising a channelring disposed radially inward of the first and second seals, radiallyoutward of the outer radial surface of the annular member, and axiallybetween the inner and outer hub bearings, the channel ring abuts anoutboard side of the inner hub bearing and forms a seal therebetween.15. The axle assembly of claim 13, wherein the channel is positioned ona compressive stress quadrant of the annular member and an unloadedsection of the inner hub bearing.
 16. The axle assembly of claim 13,wherein the channel includes a plurality of channels.
 17. The axleassembly of claim 13, wherein the outboard portion of the abutment ringabuts an inboard side of the inner hub bearing and forms a sealtherebetween.